1. What is Solar Panel Wattage?

Definition: Solar panel wattage represents the maximum power output a panel can produce under Standard Test Conditions (STC).

Purpose: It helps determine the energy production capacity of solar panels for residential, commercial, or industrial installations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W \) — Panel wattage (watts)
• \( P_{max} \) — Maximum power output at Standard Test Conditions

Explanation: The wattage of a solar panel is equal to its maximum power output rating under STC (1000W/m² irradiance, 25°C cell temperature).

3. Importance of Solar Panel Wattage

Details: Knowing a panel's wattage helps in system sizing, energy production estimation, and comparing different solar panel models.

4. Using the Calculator

Tips: Enter the Pmax value from the panel's specification sheet (typically between 250W-400W for residential panels). Value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are Standard Test Conditions (STC)?
A: STC are laboratory conditions: 1000W/m² solar irradiance, 25°C cell temperature, and air mass 1.5 spectrum.

Q2: Is real-world output the same as rated wattage?
A: No, actual output depends on sunlight intensity, temperature, shading, and other environmental factors.

Q3: What's the difference between Pmax and nominal wattage?
A: They're the same - Pmax at STC is the panel's rated wattage.

Q4: How does temperature affect wattage?
A: Power output decreases by about 0.3-0.5% per °C above 25°C (temperature coefficient).

Q5: What wattage should I choose for my home?
A: Depends on your roof space and energy needs. Higher wattage panels (350W+) require less space for the same total system power.